Summer CS 430 Practice Quiz: Chapter 10 & 11

Match the type of data storage to its definition.

1. Cache a) The fastest and most costly form of storage. 2. Main memory b) The storage medium used for data that is available to be operated on. 3. Magnetic-disk storage d) The primary medium for long-term on-line storage of data. 4. Tape Storage c) Used primarily as a backup storage medium.

Match the steps to insert a data entry into a B+ tree to their order: 1. 2. 3. 4. 5.

1. Find the correct leaf L. 2. If room in L, put data entry into L; done 3. Split L, redistribute entries evenly, copy up middle key 4. a) Insert index entry pointing into L2 into parent of L 5. If necessary,split index node recursively

Match the disk movement term to its appropriate description.

1. Seek time) Moving arms to position the disk head on track 2. Rotational delay) Time for the block to rotate under the head 3. Transfer time) Time to move the data to/from the surface

1. The time it takes for a particular hashing or indexing technique to find a particular data item, or set of items. 2. Any attribute or set of attributes with which a file may locate a record or set of records. 3. The time it takes for a particular hashing or indexing technique to delete a data item. 4. When some hash buckets are assigned more records than are others, and a bucket may overflow even as other buckets still have space, it is called ________________. 5. An indexing technique based on a uniform distribution of values across a range of buckets. 6. The time it takes for a particular hashing or indexing technique to insert a new data item. 7. An indexing technique based on a sorted ordering of the values. 8. The additional space occupied by an index structure for a particular hashing or indexing technique. 9. A type of dense index, with an index entry for every search-key value and a pointer to every record in the file, where the records pointed to by successive values in the index are not stored sequentially.

1. b) Access time 2. i) Search key 3. a) Deletion time 4. j) Skew 5. f) Hash index 6. c) Insertion time 7. e) Ordered index 8. d) Space overhead 9. g) Secondary index

Match the operation while deleting a data entry from a B+ tree to its order of sequence.

1. b) Find leaf L where entry exists. 2. c) Remove entry, replace index if necessary. 3. d) If L falls below d, try to redistribute. 4. e) If L falls below d and redistribution fails, merge L with sibling. 5. a) Recursively merge index nodes where necessary.

Match the elements below to their position in the storage-device hierarchy, according to their speed. 1. fastest 2. 3. 4. 5. slowest

1. b) cache 2. e) main memory 3. c) flash memory 4. d) disk 5. a) magnetic tapes

Match the elements below to their position in the storage-device hierarchy, according to their cost.

1. cache 2. main memory 3. flash memory 4. magnetic disk 5. optical disk 6. magnetic tapes

The primary difference between a B tree indices and a B+ tree indices is which of the following?

A B-tree eliminates the redundant storage of search-key values.

The time it takes for a particular hashing or indexing technique to find a particular data item, or set of items.

Access time

Static hashing is done by performing which of the following?

Applying a hash function h to the search key to identify the bucket to which it belongs and then searching this bucket.

Which of the following best describes the 2 parts of the representation of a record with variable-length attributes?

Data for variable length attributes Initial part with fixed length attributes

The time it takes for a particular hashing or indexing technique to delete a data item.

Deletion time

A primary index is one that includes the primary key, indexes that include only other candidate keys are called secondary indexes.

False

A search key is the same as a candidate key.

False

If we are inserting a data entry into a bucket in a static hashing table and there is no space in the bucket, we split the bucket and put the entry into the new bucket.

False

Relational schemas and other metadata about relations are stored in a structure called system cache.

False

The ability to double the directory by simply copying the directory to the lower part is accomplished because we are using the most significant bits.

False

The main advantage to a static hashing schemes is that the number of buckets is variable and memory allocation becomes simplified.

False

Which of the following are techniques used by the buffer manager to address all the disk blocks?

Forced output of blocks. Pinned blocks. Buffer replacement strategy

An indexing technique based on a uniform distribution of values across a range of buckets.

Hash index

Which of the following are NOT part of the metadata stored in a system catalog?

Index values

The time it takes for a particular hashing or indexing technique to insert a new data item.

Insertion time

The two most common tertiary storage media are:

Magnetic tapes Optical disks

An indexing technique based on a sorted ordering of the values.

Ordered index

Match the RAID level with its appropriate description. 1. RAID 0 2. RAID 1 3. RAID 1+0 4. RAID 5

REDO 1. RAID 0) Improves performance by stripping the files across multiple drives. No parity. 2. RAID 1) Provides redundancy by mirroring each of the drives. 3. RAID 1+0) Provides a striped set from a set of mirrored drives. 4. RAID 5) Allows a single drive to fail without data loss by providing block level pairity. Does not provide P + Q redundancy.

Which of the following are methods to improve reliability?

Redundancy. Mirroring. Redundant arrays of independent disks (RAID). Improving MTBF.

Any attribute or set of attributes with which a file may locate a record or set of records.

Search key

A type of dense index, with an index entry for every search-key value and a pointer to every record in the file, where the records pointed to by successive values in the index are not stored sequentially.

Secondary index

When some hash buckets are assigned more records than are others, and a bucket may overflow even as other buckets still have space, it is called ________________.

Skew

The additional space occupied by an index structure for a particular hashing or indexing technique.

Space overhead

Which of the following best describes the advantage of hashing over a tree structure for indexing ?

Storing indexes in hash structures could result in less disk I/Os.

Which of the following is true about tree-structured indexing techniques?

Support both range searches and equality searches.

A file is a collection of pages each containing a collection of records. Support must include inserts, deletes, modifies, and reads among other operations.

True

A range search is the concept of finding all records where the seach key value is less than some value and/or greater than another value.

True

Dynamic hashing techniques allow the hash function to be modified dynamically to accommodate the growth or shrinkage of the database.

True

Extendible hashing schemes solve the problems of a static hash scheme by implementing a directory of pointers to buckets and growing the directory appropriately.

True

For each view, the system catalog stores the view name and the definition of the view.

True

In a page format that consists of packed fixed length records, free space is contiguous. In a page format that consists of unpacked fixed length records, free space can be non-contiguous.

True

One of the problems with a static hashing scheme is that long overflow chains develop.

True

System catalogs are stored as as a collection of tables.

True

The buffer manager is responsible for bringing a page into RAM, and the page cannot be removed from RAM until released by the requestor(s).

True

When using a heap file organization, any record can be placed anywhere in the file where there is space for the record.

True

How many disk heads are there in a disk drive that has 4 double-sided platters, 200 cylinders, and 2000 tracks?

a) 8

Under what circumstances must a database index be updated?

a) A record is inserted into a databse. b) A record is deleted from the database.

Because all the pages cannot be brought into memory at the same time, the DBMS must bring pages into main memory as they are needed and, in the process, decide what existing page in main memory to replace to make room for the new page. Which architecture layer of a DBMS is responsible for determining which page to replace?

a) Buffer manager

Which of the following are true about B+ tree index files?

a) Insert / delete at logf(N) cost where F = fanout and N = # leaf pages. d) B+ tree is the most widely used index. c) Each node contains d

Which buffer replacement policy is optimal for a database system in all scenarios?

a) It depends - no one strategy is always optimal.

The read-write heads of all the tracks are mounted on a single assembly called a disk ______________.

arm

For a set of 100 data records with 5 fields per record, how many clustered indexes can there be?

b) 1

Which of the following are true about B+ tree-based indexing?

b) Finding the correct leaf page is faster than a binary search. a) The lowest level of the tree - called the leaf level - contains the data entries. c) It is an index structure that ensures that all paths from the root to a leaf in a given tree are of the same height.

A global depth indicator N in an extendible hashing scheme is used to identify which of the following?

b) Identifies that there are 2**N number of entries in the directory.

Which of the following are factors to be taken into account when choosing a RAID level?

b) Performance during a disk rebuild c) Performance when a disk has failed. e) Performance requirements in terms of number of I/O operations. d) Monetary cost of extra disk-storage requirements.

The average number of children in a B+ tree is called what?

b) The fan-out of the tree.

Which of the following about a database table are stored in the system catalog?

b) The file structure for the table a) The name of the table d) The integrity constraints on the table c) Attribute name and type for each attribute in the table

The policy that is used to choose and unpinned page to be swapped out is called what?

b) The replacement policy, such as LRU and clock.

A B+ tree index takes the form of a ________ tree in which every path from the root of the tree to a leaf of the tree is of the same length.

balanced

A B+ tree with a typical order of 100 and fill factor of 2/3 (i.e. fanout of 133), with a height of 4 can handle how many records?

c) 133^4

When a file is organized so that the ordering of data records is the same as or close to the ordering of data entries in some index, we say that is:

c) A clustered index.

Which of the following is true about primary and secondary indexes?

c) A primary index is one that does not allow duplicates, a secondary index is one that does.

The ith tracks of all the platters together are called the ith ______________.

cylinder

The unit of transfer betweeen disk and main memory is which of the following?

d) A set of sectors

The key attribute of a hashing function is which of the following?

d) Even distribution of the entries throughout the table.

Both the global and the local depth use the value to identify which of the following?

d) The number of bits of the value returned from the hash table to use.

In an extendible hashing scheme, the directory structure is grown when which of the following is true?

d) The size of the local depth indicatory exceeds the global indicator after the insert.

The key advantage of using a B+ tree for an index file as opposed to a hashing scheme is which of the following?

e) Range searches

Each disk ______________ has a flat circular shape.

platter

The ______________ stores information on a sector magnetically, and there is one for each side of each platter of a disk

read-write head

The ______________s are kept as close as possible to the disk surface to increase the recording density.

read-write head

A ______________ is the smallest unit of information that can be read from or written to the disk

sector

The disk platters are mounted on a ______________.

spindle

The surface of a disk is logically divided into concentric ______________.

track

When choosing a hash function to assign search key values to buckets, the function should have which of the following qualities?

uniform distribution random distribution